This invention relates to a code controlled lock device, and particularly to a dual-tone multifrequency (DTMF) code controlled lock device by which unlocking operation is effected through the transmission of pre-arranged DTMF codes so as to ensure complete security against unauthorized unlocking actions.
Conventional door locks, such as key-operated locks, combination locks, push-button locks, etc., suffer a common problem, i.e. the unlocking portions of the locks are all exposed on an outside surface of the door. These exposed portions of the locks are susceptible to unauthorized unlocking actions and to being wrecked by burglars. Therefore, security of the conventional locks cannot be ensured.